1. Field of the Invention
This invention relates to a structure for fixing a terminal end of a cable for supporting a bridge beam of a skew bridge or a cable for supporting a hanging structure, and more particularly, an improvement about a press fixing grip system in which a press fixing grip is fixed to a terminal end of the PC steel twisted wire constituting a cable and the press fixing grip is engaged with and fixed to a fixing plate fixed to an inner side of an anchor socket.
2. Description of the Related Art
Cables 3 for supporting a bridge beam 11 in the skew bridge shown in FIG. 1 are made such that a desired number of bundles of the PC steel twisted wires are bundled and as a system employed for fixing the terminal ends of the wires nowadays, there is provided a press fixing grip system.
The press fixing grip system is constructed such that a fixing plate 2xe2x80x2 is fixed inside the anchor socket 1xe2x80x2 as shown in FIG. 8 and the end part of the press fixing grip 5xe2x80x2 fixed to an outer side of the terminal end of each of the PC steel twisted wires 4xe2x80x2 is engaged with an edge of each of insertion holes passed through and opened at the fixing plate 2xe2x80x2 and then fixed. Then, the PC steel twisted wires inserted into and passed through the fixing plate except the central part thereof are inclined in a slant manner and fixed in such a way that they may be dispersed from the central part toward an outside part in a radial direction.
The aforesaid related art structure is a structure in which a tensile load of the cable is supported by the fixing plate and a press fixing grip press fixed and fixed to an outside part of a terminal end of the PC steel twisted wire and further epoxy resin (APS compound) 8 is fed into a space between the press fixing grips arranged outside the fixing plate to endure against a varying stress caused by an active load.
Accordingly, in this case, the fixing part capable of being endured against a tensile load is defined as a fixing part having a range extending up to the end part of the press fixing grip engaged with the fixing plate, resulting in that a thickness Txe2x80x2 at the fixing part is formed thick.
In addition, since the bundled PC steel twisted wires are fixed in an inclined state in such a way that the press fixing grips are dispersed in a radial direction, a center at an inlet side of the insertion hole and a center at an outlet side of the insertion hole opened at the fixing plate are displaced and then a diameter Lxe2x80x2 of the fixing plate is also set to be large.
If a thickness and a diameter of the fixing plate are set to be large, it is naturally required to provide a large-sized anchor socket having the fixing plate installed therein and their sizes may influence against its handling work at site.
This invention has been invented in reference to the problem of the related art described above and it is an object of the present invention to provide a bridge cable fixing structure in which an outer diameter and a thickness of a fixing plate for accepting a tensile load of the cable can be reduced and a size of the anchor socket can be decreased.
A technical means applied by the present invention in order to solve the aforesaid problem consists in a bridge cable fixing structure in which some press fixing grips are fixed to terminal ends of PC steel twisted wires and the side ends of the press fixing grips are engaged with the fixing plate inside an anchor socket, wherein insertion holes of about same diameter into which PC steel twisted wires are inserted are opened at one side of said fixing plate and the press fixing grip engaging holes to which the outer circumferential surfaces of the press fixing grips are closely contacted on axis lines of said insertion holes are communicated with and opened at the other side of said fixing plate, and the side ends and the outer circumferential surfaces of the press fixing grips are closely contacted to and engaged with the fixing plate.
A large number of insertion holes (fixing grip engaging holes on co-axial lines) opened at the fixing plate are arranged such that their axes are set in parallel with a center of the fixing plate and equally spaced apart around the fixing plate in a radial direction.
In addition, the press fixing grip engaging holes at the fixing plate are opened at least a half of or more than half of the thickness of the fixing plate.
Further, the aforesaid fixing plate may be applied as either a separate structure which is separate from the anchor socket or an integral structure which is integral with the socket.
In accordance with the aforesaid means, if the circumferential edge at the side part of the fixing plate where the insertion holes are opened is supported by the anchor socket and a tensile load is applied to the cables, one side where the insertion holes are formed is applied as a tensile side and the other side where the fixing grip engaging holes at the opposite side are opened is applied as a compression side with a center of the thickness of the fixing plate (a neutral axis) being applied as an interface. Then, the fixing grips inserted into the fixing grip engaging holes formed at the compression side are pushed with the hole circumferential wall surfaces of the fixing grip engaging holes so as to prevent the fixing grips from being pulled out of the PC steel twisted wires and their diameters from being expanded (bulged out). With such an arrangement as above, the fixing grips are integrally assembled with the fixing plate.
Accordingly, it can be considered that some fixing grips arranged and fixed to the compression side of the fixing plate have effective sectional area, thereby it becomes possible that a lost amount of section caused by opening the fixing grip engaging holes is restricted to a minimum amount and a thickness of the fixing plate can be made thin as compared with that of the related art structure.
Further, the fixing grips can be integrally assembled with the fixing plate under the aforesaid configuration and each of the insertion holes is opened in parallel with the center of the fixing plate, resulting in that a diameter of the fixing plate can be made small as compared with that of the related art structure.